1. Field of the Invention
This invention relates to telescopic chutes used for directing and dispensing aggregate and cementitious materials from a mixer truck to a point remote from the truck. The telescopic chute of this invention is adapted for use on mixer trucks of the type which normally mix and transport concrete.
2. Description of the Prior Art
The majority of chutes now in use for directing and dispensing ready mix concrete and the like from mixer trucks are comprised of several separate trough-like sections which are manually hooked together at the beginning of each job to form one extended chute. Once assembled, the chutes receive the concrete from the dispensing end of the drum of the mixer truck, and transport the flowable concrete using gravity feed a significant distance from the mixer truck. Extended chutes eliminate the need to manually transport the concrete with shovels and or wheelbarrows. The hook-together chute sections are not only heavy, cumbersome, and somewhat dangerous due to the weight to assemble and disassemble, but require storage space on the exterior of the mixer truck after the job is completed.
In order to solve some of the problems associated with separate hook-together chutes, telescopic chutes for dispensing concrete from a truck have been tried in the past. Telescopic chutes are generally comprised of a plurality of overlapping trough-like sections which can be retracted into a compact form for transportation on the mixer truck, and extended for dispensing remote of the truck. Although telescopic chutes for dispensing aggregate mixtures from mixer trucks are not new to the field, their use has not gained any appreciable popularity up to the present.
There exists problems in the past art telescopic chutes which have made their use inconvenient and excessively expensive for profitable use. The major problem associated with past art telescopic chute structures for mixer trucks has been the cost of maintenance over an extended period of time. Aggregate materials containing rock and sand are extremely abrasive, and the chemicals and water mixed with the rock to form concrete are corrosive to chutes, particularly chutes made of metal. Abrasion and corrosion of these metal chutes significantly reduces their functional lifespan. Often a metal chute will have a lifespan as short as eighteen months. Abrasion from the rock and sand also greatly reduces the functional life of sliding interlocks and guide tracks typically used on telescopic chute structures. Telescopic chute structures are quite expensive to build or purchase when compared to simpler more conventional hook-together chute structures, and when the sections of the telescopic chute are worn, it becomes prohibitively expensive, or not cost effective for most companies to replace the chute sections, particularly when replacement may be necessary every 18 months. The high maintenance expense associated with telescopic chutes is recognized by those who have attempted to use this type of structure in the past on mixer trucks
In a patent search performed at the U.S. Patent and Trademark Office, the following past art documents were determined to teach devices somewhat similar to my improved telescopic chute.
A U.S. patent issued to J. F. Oury on Jan. 17, 1961, U.S. Pat. No. 2,968,382, teaches a telescopic chute comprised of smaller individual chute sections which apparently must be entirely replaced when component sections become worn or damaged, primarily the trough section of the chute. Controls for manipulating the extension and angle of the chute are located at the rear of the truck where it may be difficult to see the actual dispensing of the concrete at the distal end of the chute.
L. P. Chapdelaine was granted U.S. Pat. No. 3,157,262, on Nov. 17, 1964, for a telescopic chute operating on a system of cables and pulleys. This device does not appear to include self-cleaning structuring of the chutes and would more than likely experience extreme wear and tear, requiring replacement of entire chute sections.
The U.S. Patent granted to N. S. Hansen on Aug. 8, 1967, U.S. Pat. No. 3,334,872, shows a mixer truck having a front mounted discharge end and chute where the driver can better see and control the distribution of the concrete. Although Hansen mentions controls for the distribution of the concrete being operated from the cab of the vehicle or other convenient location, he does not anticipate the use of telescopic chutes. No mention is made of individual detachable components of the chute providing for inexpensive replacement of worn sections.
Other past art patents examined in the search which taught telescopic chute structures were considered indicative of telescopic chutes, and having similar problems associated therewith as previously presented in the Oury and Chapdelaine devices.
Also typical of dispensing chutes is the location of the control levers or switches for manipulating the position of the chutes, whether of the telescopic type or more conventional hook-together type chute. Typically, controls are permanently located in fixed locations on the truck. The truck does not seem to be the ideal position for controlling movement of the chute when the dispensing end of the chute may be twenty feet away, and already has a person standing there attempting to monitor the discharge from the chute.
None of the previously mentioned past art devices described power actuated telescopic chutes having replaceable liners. Some vaguely suggest replacement of the entire individual sections of the chute, and not specific components of the chute sections which wear out more quickly than others, such as the interior of the trough which contacts the concrete, or the guide and support track components.